非病毒载体H1s-EGFc的构建及其功能的初步研究

目的 探讨和构建一种用于靶向性基因治疗的非病毒载体。方法 采用基因工程的方法构建H1s—EGFc融合蛋白表达载体,在毕赤酵母表达系统中获得分泌表达的融合蛋白。使用阴离子交换柱及分子筛进行纯化。制备H1s—EGFc融合蛋白与pKG杀伤基因表达重组体的复合物。选用表皮生长因子受体高表达的HeLa细胞及表皮生长因子受体不表达的Jurkat细胞进行复合物特异性杀伤活性测试。结果 构建并表达了H1s—EGFc融合蛋白,所获融合蛋白纯度可达90％以上。该融合蛋白能够有效地包装杀伤基因表达载体,将其导入表皮生长因子受体特异性表达的肿瘤细胞中,达到靶向性杀伤作用,当融合蛋白／杀伤基因复合物使用剂量分别是3、6、9μg／ml时,杀伤率分别为30．6％、36．2％和58．1％;而对表皮生长因子受体不表达的细胞无杀伤作用。结论 融合蛋白H1s—EGFc能够有效地用于功能基因的包装及转运,可以作为非病毒载体应用于恶性肿瘤的靶向性基因治疗。

Construction of a non-viral vector H1s-EGFc and a preliminary study on its function

OBJECTIVE: To construct a non-viral vector for targeting cancer gene therapy. METHODS: The coding sequence of H1s-EGFc was inserted into the expression vectors of Pichia pastoris, and the fusion protein was expressed in secretary way. H1s-EGFc was purified by anion exchange chromatography and size exclusion chromatography. H1s-EGFc fusion protein and "killing gene" expression recombinant pKG plasmid DNA were dissolved in serum-free RPMI-1640 culture to produce H1s-EGFc/pKG complex. HeLa cells, an epidermal growth factor receptor (EGFR) highly expressing cell line, and Jurkat cells, an EGFR non-expressing cell line, were cultured and transfected with H1s-EGFc/pKG complex of different concentrations. Trypan blue staining was used to calculate the number of live cells and the killing rate of H1s-EGFc/pKG. RESULTS: H1s-EGFc fusion protein was constructed and expressed with a purity of over 90%. When the concentrations of H1s-EGFc/pKG complex were 3 microg/ml, 6 microg/ml, and 9 microg/ml respectively the killing rates were 30.6%, 36.2%, and 58.1% respectively. CONCLUSION: The fusion protein H1s-EGFc binds functional gene efficiently and targets it into specific cells. It can be used as non-viral vector in target cancer gene therapy.